bug#20322: 25.0.50; indent-tabs-mode should default to nil

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 14 Apr 2015 23:24:54 +0300
> From: Dmitry Gutov <dgutov@yandex.ru>
> CC: 20322@debbugs.gnu.org
> 
> On 04/14/2015 06:59 PM, Eli Zaretskii wrote:
> 
> > Then by all means let's fix those modes whose defaults aren't.
> 
> So, most of them?

If it turns out that most of the modes need indent-tabs-mode set to
nil, you can make it the default in prog-mode, or even in fundamental
mode.  As long as the modes that don't need to avoid tabs are changed
to have the same default as now, I won't object.

> Like I said, in the end that would call for the change of the
> default value. In the meantime, should we have an
> xxx-indent-tabs-mode variable per major mode?

I don't see a need for a mode-specific variable in this case; do you?

> I understand that C (and, to lesser extent, C++) have a lot of history, 
> and a lot of variance in their communities.
> 
> But the only semi-official style guide I could find that advises to use 
> tabs in the Linux kernel one: 
> http://www.maultech.com/chrislott/resources/cstyle/LinuxKernelCodingStyle.txt
> 
> The GNU coding style, to the best of my understanding, does not mention 
> tabs at all.

Let's just honor history in this case, OK?

> > The vast majority of people I work with use tabs, FWIW.
> 
> Do they use 8-column offsets, then?

No (that's how I know they use tabs in the first place!).

> >> Even folks who want tabs have to configure stuff, because of our
> >> `tab-width' default (which is indeed something we cannot change now):
> >> http://stackoverflow.com/a/21788651/615245
> >
> > Our tab-width default is simply the default tab width everywhere.
> 
> I'm not sure what you mean by that, but my point was, the defaults are 
> not suitable as-is (even) for a certain part of our users that use tabs.

For a customizable option, this is not an issue.  I can understand
that the new generation may want to get rid of tabs, but since most of
that generation don't work in C/C++, I think we can leave those alone
for now.